The cruise control won't engage

I have a 97 Acura CL 3.0 Litre premium, cruise control lights up when I press the power switch, also the dash lights up when I engage, but the cruise control won't engage. Vacuum?

As previously stated the cruise control is presently inop. As a secondary symptom, I noticed what sounds like a vacuum leak when the car is at idle. When I give it some throttle the hissing seems to subside. Could this be the reason behind the Cruise control not working? There is no rough engine idle. The hissing also seems to occur whenever the heater/ defroster is engaged, and seems to lessen and sometimes stop when disengaged.

We just purchased this car and even though it's a 97, the car is super clean and we do love the car. I just want to get everything working to insure a long and as trouble free experience as possible. I hope to enjoy the Acura/Honda superior engineering for a while, I take very good care of my cars and do all required maintenance to keep them as trouble free as possible. I hope you can shed some light on my cruise control issue, thanking you in advance, Carl Scheel